Integrals saved by the SEWARD module are stored in the Atomic Orbital (AO) basis. Some programs have their own procedures to transform the integrals into the Molecular Orbital (MO) basis. The MOLCAS MOTRA module performs this task for Configuration Interaction (CI), Coupled- and Modified Coupled-Pair (CPF and MCPF, respectively) and Coupled-Cluster (CC) calculations.
Figure 3.9 contains the motra input information for our continuing water calculation. We firstly specify that the RASSCF module interface file will be the source of the orbitals using the keyword JOBIph. The keyword FROZen is used to specify the number of orbitals in each symmetry which will not be correlated in subsequent calculations. This can also be performed in the corresponding MRCI, CPF or CC programs but is more efficient to freeze them here. Virtual orbitals can be deleted using the DELEte keyword.
The motra section of the output is short and self explanatory. The integral files produced by the seward module, ONEINT and ORDINT, are used as input by the motra module which produces the transformed symbolic files TRAONE and TRAINT, respectively. In our case, the files are called water.TraOne and water.TraInt, respectively.
Figure 3.9. Sample input requesting the motra module to transform the integrals stored in the JOBIPH files to the molecular orbital basis.
&MOTRA &END JobIph Frozen 1 0 0 0 *Delete * 1 0 0 0 End of Input
The motra module also requires input orbitals. If the LUMOrb keyword is specified the orbitals are taken from the INPORB file which can be any formated orbital file such as water.ScfOrb or water.RasOrb. The JOBIph keyword causes the motra module to read the required orbitals from the JOBIPH file.